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IP subnet calculator

Type an address with its prefix or mask to see the network, its usable range and masks. Split it into smaller subnets, or look up any prefix in the reference tables.

Network91.96.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
91.96.0.0
Broadcast address
91.111.255.255
First usable
91.96.0.1
Last usable
91.111.255.254
Usable hosts
1,048,574 (1,048,576 less the network and broadcast addresses)
Subnet mask
255.240.0.0
Wildcard mask
0.15.255.255 (Cisco ACLs, OSPF)
Prefix length
/12
Type
Public public
Old class
A (default /8)
As numbers
Hex 5B600000 · Integer 1533018112 to 1534066687
Reverse DNS zones
96.91.in-addr.arpa
97.91.in-addr.arpa
98.91.in-addr.arpa
99.91.in-addr.arpa
100.91.in-addr.arpa
101.91.in-addr.arpa
102.91.in-addr.arpa
103.91.in-addr.arpa
104.91.in-addr.arpa
105.91.in-addr.arpa
106.91.in-addr.arpa
107.91.in-addr.arpa
108.91.in-addr.arpa
109.91.in-addr.arpa
110.91.in-addr.arpa
111.91.in-addr.arpa
/12 is not on a 8-bit boundary, so it takes 16 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01011011.01100000.00000000.0000000091.96.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network01011011.01100000.00000000.0000000091.96.0.0
Broadcast01011011.01101111.11111111.1111111191.111.255.255
Split into smaller subnets/21
/13 (2)/14 (4)/15 (8)/16 (16)/17 (32)/18 (64)/19 (128)/20 (256)/21 (512)/22 (1,024)/23 (2,048)/24 (4,096)

91.96.0.0/12 makes 512 subnets of /21; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
191.96.0.0/2191.96.0.1 to 91.96.7.25491.96.7.2552,046
291.96.8.0/2191.96.8.1 to 91.96.15.25491.96.15.2552,046
391.96.16.0/2191.96.16.1 to 91.96.23.25491.96.23.2552,046
491.96.24.0/2191.96.24.1 to 91.96.31.25491.96.31.2552,046
591.96.32.0/2191.96.32.1 to 91.96.39.25491.96.39.2552,046
691.96.40.0/2191.96.40.1 to 91.96.47.25491.96.47.2552,046
791.96.48.0/2191.96.48.1 to 91.96.55.25491.96.55.2552,046
891.96.56.0/2191.96.56.1 to 91.96.63.25491.96.63.2552,046
991.96.64.0/2191.96.64.1 to 91.96.71.25491.96.71.2552,046
1091.96.72.0/2191.96.72.1 to 91.96.79.25491.96.79.2552,046
1191.96.80.0/2191.96.80.1 to 91.96.87.25491.96.87.2552,046
1291.96.88.0/2191.96.88.1 to 91.96.95.25491.96.95.2552,046
1391.96.96.0/2191.96.96.1 to 91.96.103.25491.96.103.2552,046
1491.96.104.0/2191.96.104.1 to 91.96.111.25491.96.111.2552,046
1591.96.112.0/2191.96.112.1 to 91.96.119.25491.96.119.2552,046
1691.96.120.0/2191.96.120.1 to 91.96.127.25491.96.127.2552,046
1791.96.128.0/2191.96.128.1 to 91.96.135.25491.96.135.2552,046
1891.96.136.0/2191.96.136.1 to 91.96.143.25491.96.143.2552,046
1991.96.144.0/2191.96.144.1 to 91.96.151.25491.96.151.2552,046
2091.96.152.0/2191.96.152.1 to 91.96.159.25491.96.159.2552,046
2191.96.160.0/2191.96.160.1 to 91.96.167.25491.96.167.2552,046
2291.96.168.0/2191.96.168.1 to 91.96.175.25491.96.175.2552,046
2391.96.176.0/2191.96.176.1 to 91.96.183.25491.96.183.2552,046
2491.96.184.0/2191.96.184.1 to 91.96.191.25491.96.191.2552,046
2591.96.192.0/2191.96.192.1 to 91.96.199.25491.96.199.2552,046
2691.96.200.0/2191.96.200.1 to 91.96.207.25491.96.207.2552,046
2791.96.208.0/2191.96.208.1 to 91.96.215.25491.96.215.2552,046
2891.96.216.0/2191.96.216.1 to 91.96.223.25491.96.223.2552,046
2991.96.224.0/2191.96.224.1 to 91.96.231.25491.96.231.2552,046
3091.96.232.0/2191.96.232.1 to 91.96.239.25491.96.239.2552,046
3191.96.240.0/2191.96.240.1 to 91.96.247.25491.96.247.2552,046
3291.96.248.0/2191.96.248.1 to 91.96.255.25491.96.255.2552,046
3391.97.0.0/2191.97.0.1 to 91.97.7.25491.97.7.2552,046
3491.97.8.0/2191.97.8.1 to 91.97.15.25491.97.15.2552,046
3591.97.16.0/2191.97.16.1 to 91.97.23.25491.97.23.2552,046
3691.97.24.0/2191.97.24.1 to 91.97.31.25491.97.31.2552,046
3791.97.32.0/2191.97.32.1 to 91.97.39.25491.97.39.2552,046
3891.97.40.0/2191.97.40.1 to 91.97.47.25491.97.47.2552,046
3991.97.48.0/2191.97.48.1 to 91.97.55.25491.97.55.2552,046
4091.97.56.0/2191.97.56.1 to 91.97.63.25491.97.63.2552,046
4191.97.64.0/2191.97.64.1 to 91.97.71.25491.97.71.2552,046
4291.97.72.0/2191.97.72.1 to 91.97.79.25491.97.79.2552,046
4391.97.80.0/2191.97.80.1 to 91.97.87.25491.97.87.2552,046
4491.97.88.0/2191.97.88.1 to 91.97.95.25491.97.95.2552,046
4591.97.96.0/2191.97.96.1 to 91.97.103.25491.97.103.2552,046
4691.97.104.0/2191.97.104.1 to 91.97.111.25491.97.111.2552,046
4791.97.112.0/2191.97.112.1 to 91.97.119.25491.97.119.2552,046
4891.97.120.0/2191.97.120.1 to 91.97.127.25491.97.127.2552,046
4991.97.128.0/2191.97.128.1 to 91.97.135.25491.97.135.2552,046
5091.97.136.0/2191.97.136.1 to 91.97.143.25491.97.143.2552,046
5191.97.144.0/2191.97.144.1 to 91.97.151.25491.97.151.2552,046
5291.97.152.0/2191.97.152.1 to 91.97.159.25491.97.159.2552,046
5391.97.160.0/2191.97.160.1 to 91.97.167.25491.97.167.2552,046
5491.97.168.0/2191.97.168.1 to 91.97.175.25491.97.175.2552,046
5591.97.176.0/2191.97.176.1 to 91.97.183.25491.97.183.2552,046
5691.97.184.0/2191.97.184.1 to 91.97.191.25491.97.191.2552,046
5791.97.192.0/2191.97.192.1 to 91.97.199.25491.97.199.2552,046
5891.97.200.0/2191.97.200.1 to 91.97.207.25491.97.207.2552,046
5991.97.208.0/2191.97.208.1 to 91.97.215.25491.97.215.2552,046
6091.97.216.0/2191.97.216.1 to 91.97.223.25491.97.223.2552,046
6191.97.224.0/2191.97.224.1 to 91.97.231.25491.97.231.2552,046
6291.97.232.0/2191.97.232.1 to 91.97.239.25491.97.239.2552,046
6391.97.240.0/2191.97.240.1 to 91.97.247.25491.97.247.2552,046
6491.97.248.0/2191.97.248.1 to 91.97.255.25491.97.255.2552,046
6591.98.0.0/2191.98.0.1 to 91.98.7.25491.98.7.2552,046
6691.98.8.0/2191.98.8.1 to 91.98.15.25491.98.15.2552,046
6791.98.16.0/2191.98.16.1 to 91.98.23.25491.98.23.2552,046
6891.98.24.0/2191.98.24.1 to 91.98.31.25491.98.31.2552,046
6991.98.32.0/2191.98.32.1 to 91.98.39.25491.98.39.2552,046
7091.98.40.0/2191.98.40.1 to 91.98.47.25491.98.47.2552,046
7191.98.48.0/2191.98.48.1 to 91.98.55.25491.98.55.2552,046
7291.98.56.0/2191.98.56.1 to 91.98.63.25491.98.63.2552,046
7391.98.64.0/2191.98.64.1 to 91.98.71.25491.98.71.2552,046
7491.98.72.0/2191.98.72.1 to 91.98.79.25491.98.79.2552,046
7591.98.80.0/2191.98.80.1 to 91.98.87.25491.98.87.2552,046
7691.98.88.0/2191.98.88.1 to 91.98.95.25491.98.95.2552,046
7791.98.96.0/2191.98.96.1 to 91.98.103.25491.98.103.2552,046
7891.98.104.0/2191.98.104.1 to 91.98.111.25491.98.111.2552,046
7991.98.112.0/2191.98.112.1 to 91.98.119.25491.98.119.2552,046
8091.98.120.0/2191.98.120.1 to 91.98.127.25491.98.127.2552,046
8191.98.128.0/2191.98.128.1 to 91.98.135.25491.98.135.2552,046
8291.98.136.0/2191.98.136.1 to 91.98.143.25491.98.143.2552,046
8391.98.144.0/2191.98.144.1 to 91.98.151.25491.98.151.2552,046
8491.98.152.0/2191.98.152.1 to 91.98.159.25491.98.159.2552,046
8591.98.160.0/2191.98.160.1 to 91.98.167.25491.98.167.2552,046
8691.98.168.0/2191.98.168.1 to 91.98.175.25491.98.175.2552,046
8791.98.176.0/2191.98.176.1 to 91.98.183.25491.98.183.2552,046
8891.98.184.0/2191.98.184.1 to 91.98.191.25491.98.191.2552,046
8991.98.192.0/2191.98.192.1 to 91.98.199.25491.98.199.2552,046
9091.98.200.0/2191.98.200.1 to 91.98.207.25491.98.207.2552,046
9191.98.208.0/2191.98.208.1 to 91.98.215.25491.98.215.2552,046
9291.98.216.0/2191.98.216.1 to 91.98.223.25491.98.223.2552,046
9391.98.224.0/2191.98.224.1 to 91.98.231.25491.98.231.2552,046
9491.98.232.0/2191.98.232.1 to 91.98.239.25491.98.239.2552,046
9591.98.240.0/2191.98.240.1 to 91.98.247.25491.98.247.2552,046
9691.98.248.0/2191.98.248.1 to 91.98.255.25491.98.255.2552,046
9791.99.0.0/2191.99.0.1 to 91.99.7.25491.99.7.2552,046
9891.99.8.0/2191.99.8.1 to 91.99.15.25491.99.15.2552,046
9991.99.16.0/2191.99.16.1 to 91.99.23.25491.99.23.2552,046
10091.99.24.0/2191.99.24.1 to 91.99.31.25491.99.31.2552,046
10191.99.32.0/2191.99.32.1 to 91.99.39.25491.99.39.2552,046
10291.99.40.0/2191.99.40.1 to 91.99.47.25491.99.47.2552,046
10391.99.48.0/2191.99.48.1 to 91.99.55.25491.99.55.2552,046
10491.99.56.0/2191.99.56.1 to 91.99.63.25491.99.63.2552,046
10591.99.64.0/2191.99.64.1 to 91.99.71.25491.99.71.2552,046
10691.99.72.0/2191.99.72.1 to 91.99.79.25491.99.79.2552,046
10791.99.80.0/2191.99.80.1 to 91.99.87.25491.99.87.2552,046
10891.99.88.0/2191.99.88.1 to 91.99.95.25491.99.95.2552,046
10991.99.96.0/2191.99.96.1 to 91.99.103.25491.99.103.2552,046
11091.99.104.0/2191.99.104.1 to 91.99.111.25491.99.111.2552,046
11191.99.112.0/2191.99.112.1 to 91.99.119.25491.99.119.2552,046
11291.99.120.0/2191.99.120.1 to 91.99.127.25491.99.127.2552,046
11391.99.128.0/2191.99.128.1 to 91.99.135.25491.99.135.2552,046
11491.99.136.0/2191.99.136.1 to 91.99.143.25491.99.143.2552,046
11591.99.144.0/2191.99.144.1 to 91.99.151.25491.99.151.2552,046
11691.99.152.0/2191.99.152.1 to 91.99.159.25491.99.159.2552,046
11791.99.160.0/2191.99.160.1 to 91.99.167.25491.99.167.2552,046
11891.99.168.0/2191.99.168.1 to 91.99.175.25491.99.175.2552,046
11991.99.176.0/2191.99.176.1 to 91.99.183.25491.99.183.2552,046
12091.99.184.0/2191.99.184.1 to 91.99.191.25491.99.191.2552,046
12191.99.192.0/2191.99.192.1 to 91.99.199.25491.99.199.2552,046
12291.99.200.0/2191.99.200.1 to 91.99.207.25491.99.207.2552,046
12391.99.208.0/2191.99.208.1 to 91.99.215.25491.99.215.2552,046
12491.99.216.0/2191.99.216.1 to 91.99.223.25491.99.223.2552,046
12591.99.224.0/2191.99.224.1 to 91.99.231.25491.99.231.2552,046
12691.99.232.0/2191.99.232.1 to 91.99.239.25491.99.239.2552,046
12791.99.240.0/2191.99.240.1 to 91.99.247.25491.99.247.2552,046
12891.99.248.0/2191.99.248.1 to 91.99.255.25491.99.255.2552,046
12991.100.0.0/2191.100.0.1 to 91.100.7.25491.100.7.2552,046
13091.100.8.0/2191.100.8.1 to 91.100.15.25491.100.15.2552,046
13191.100.16.0/2191.100.16.1 to 91.100.23.25491.100.23.2552,046
13291.100.24.0/2191.100.24.1 to 91.100.31.25491.100.31.2552,046
13391.100.32.0/2191.100.32.1 to 91.100.39.25491.100.39.2552,046
13491.100.40.0/2191.100.40.1 to 91.100.47.25491.100.47.2552,046
13591.100.48.0/2191.100.48.1 to 91.100.55.25491.100.55.2552,046
13691.100.56.0/2191.100.56.1 to 91.100.63.25491.100.63.2552,046
13791.100.64.0/2191.100.64.1 to 91.100.71.25491.100.71.2552,046
13891.100.72.0/2191.100.72.1 to 91.100.79.25491.100.79.2552,046
13991.100.80.0/2191.100.80.1 to 91.100.87.25491.100.87.2552,046
14091.100.88.0/2191.100.88.1 to 91.100.95.25491.100.95.2552,046
14191.100.96.0/2191.100.96.1 to 91.100.103.25491.100.103.2552,046
14291.100.104.0/2191.100.104.1 to 91.100.111.25491.100.111.2552,046
14391.100.112.0/2191.100.112.1 to 91.100.119.25491.100.119.2552,046
14491.100.120.0/2191.100.120.1 to 91.100.127.25491.100.127.2552,046
14591.100.128.0/2191.100.128.1 to 91.100.135.25491.100.135.2552,046
14691.100.136.0/2191.100.136.1 to 91.100.143.25491.100.143.2552,046
14791.100.144.0/2191.100.144.1 to 91.100.151.25491.100.151.2552,046
14891.100.152.0/2191.100.152.1 to 91.100.159.25491.100.159.2552,046
14991.100.160.0/2191.100.160.1 to 91.100.167.25491.100.167.2552,046
15091.100.168.0/2191.100.168.1 to 91.100.175.25491.100.175.2552,046
15191.100.176.0/2191.100.176.1 to 91.100.183.25491.100.183.2552,046
15291.100.184.0/2191.100.184.1 to 91.100.191.25491.100.191.2552,046
15391.100.192.0/2191.100.192.1 to 91.100.199.25491.100.199.2552,046
15491.100.200.0/2191.100.200.1 to 91.100.207.25491.100.207.2552,046
15591.100.208.0/2191.100.208.1 to 91.100.215.25491.100.215.2552,046
15691.100.216.0/2191.100.216.1 to 91.100.223.25491.100.223.2552,046
15791.100.224.0/2191.100.224.1 to 91.100.231.25491.100.231.2552,046
15891.100.232.0/2191.100.232.1 to 91.100.239.25491.100.239.2552,046
15991.100.240.0/2191.100.240.1 to 91.100.247.25491.100.247.2552,046
16091.100.248.0/2191.100.248.1 to 91.100.255.25491.100.255.2552,046
16191.101.0.0/2191.101.0.1 to 91.101.7.25491.101.7.2552,046
16291.101.8.0/2191.101.8.1 to 91.101.15.25491.101.15.2552,046
16391.101.16.0/2191.101.16.1 to 91.101.23.25491.101.23.2552,046
16491.101.24.0/2191.101.24.1 to 91.101.31.25491.101.31.2552,046
16591.101.32.0/2191.101.32.1 to 91.101.39.25491.101.39.2552,046
16691.101.40.0/2191.101.40.1 to 91.101.47.25491.101.47.2552,046
16791.101.48.0/2191.101.48.1 to 91.101.55.25491.101.55.2552,046
16891.101.56.0/2191.101.56.1 to 91.101.63.25491.101.63.2552,046
16991.101.64.0/2191.101.64.1 to 91.101.71.25491.101.71.2552,046
17091.101.72.0/2191.101.72.1 to 91.101.79.25491.101.79.2552,046
17191.101.80.0/2191.101.80.1 to 91.101.87.25491.101.87.2552,046
17291.101.88.0/2191.101.88.1 to 91.101.95.25491.101.95.2552,046
17391.101.96.0/2191.101.96.1 to 91.101.103.25491.101.103.2552,046
17491.101.104.0/2191.101.104.1 to 91.101.111.25491.101.111.2552,046
17591.101.112.0/2191.101.112.1 to 91.101.119.25491.101.119.2552,046
17691.101.120.0/2191.101.120.1 to 91.101.127.25491.101.127.2552,046
17791.101.128.0/2191.101.128.1 to 91.101.135.25491.101.135.2552,046
17891.101.136.0/2191.101.136.1 to 91.101.143.25491.101.143.2552,046
17991.101.144.0/2191.101.144.1 to 91.101.151.25491.101.151.2552,046
18091.101.152.0/2191.101.152.1 to 91.101.159.25491.101.159.2552,046
18191.101.160.0/2191.101.160.1 to 91.101.167.25491.101.167.2552,046
18291.101.168.0/2191.101.168.1 to 91.101.175.25491.101.175.2552,046
18391.101.176.0/2191.101.176.1 to 91.101.183.25491.101.183.2552,046
18491.101.184.0/2191.101.184.1 to 91.101.191.25491.101.191.2552,046
18591.101.192.0/2191.101.192.1 to 91.101.199.25491.101.199.2552,046
18691.101.200.0/2191.101.200.1 to 91.101.207.25491.101.207.2552,046
18791.101.208.0/2191.101.208.1 to 91.101.215.25491.101.215.2552,046
18891.101.216.0/2191.101.216.1 to 91.101.223.25491.101.223.2552,046
18991.101.224.0/2191.101.224.1 to 91.101.231.25491.101.231.2552,046
19091.101.232.0/2191.101.232.1 to 91.101.239.25491.101.239.2552,046
19191.101.240.0/2191.101.240.1 to 91.101.247.25491.101.247.2552,046
19291.101.248.0/2191.101.248.1 to 91.101.255.25491.101.255.2552,046
19391.102.0.0/2191.102.0.1 to 91.102.7.25491.102.7.2552,046
19491.102.8.0/2191.102.8.1 to 91.102.15.25491.102.15.2552,046
19591.102.16.0/2191.102.16.1 to 91.102.23.25491.102.23.2552,046
19691.102.24.0/2191.102.24.1 to 91.102.31.25491.102.31.2552,046
19791.102.32.0/2191.102.32.1 to 91.102.39.25491.102.39.2552,046
19891.102.40.0/2191.102.40.1 to 91.102.47.25491.102.47.2552,046
19991.102.48.0/2191.102.48.1 to 91.102.55.25491.102.55.2552,046
20091.102.56.0/2191.102.56.1 to 91.102.63.25491.102.63.2552,046
20191.102.64.0/2191.102.64.1 to 91.102.71.25491.102.71.2552,046
20291.102.72.0/2191.102.72.1 to 91.102.79.25491.102.79.2552,046
20391.102.80.0/2191.102.80.1 to 91.102.87.25491.102.87.2552,046
20491.102.88.0/2191.102.88.1 to 91.102.95.25491.102.95.2552,046
20591.102.96.0/2191.102.96.1 to 91.102.103.25491.102.103.2552,046
20691.102.104.0/2191.102.104.1 to 91.102.111.25491.102.111.2552,046
20791.102.112.0/2191.102.112.1 to 91.102.119.25491.102.119.2552,046
20891.102.120.0/2191.102.120.1 to 91.102.127.25491.102.127.2552,046
20991.102.128.0/2191.102.128.1 to 91.102.135.25491.102.135.2552,046
21091.102.136.0/2191.102.136.1 to 91.102.143.25491.102.143.2552,046
21191.102.144.0/2191.102.144.1 to 91.102.151.25491.102.151.2552,046
21291.102.152.0/2191.102.152.1 to 91.102.159.25491.102.159.2552,046
21391.102.160.0/2191.102.160.1 to 91.102.167.25491.102.167.2552,046
21491.102.168.0/2191.102.168.1 to 91.102.175.25491.102.175.2552,046
21591.102.176.0/2191.102.176.1 to 91.102.183.25491.102.183.2552,046
21691.102.184.0/2191.102.184.1 to 91.102.191.25491.102.191.2552,046
21791.102.192.0/2191.102.192.1 to 91.102.199.25491.102.199.2552,046
21891.102.200.0/2191.102.200.1 to 91.102.207.25491.102.207.2552,046
21991.102.208.0/2191.102.208.1 to 91.102.215.25491.102.215.2552,046
22091.102.216.0/2191.102.216.1 to 91.102.223.25491.102.223.2552,046
22191.102.224.0/2191.102.224.1 to 91.102.231.25491.102.231.2552,046
22291.102.232.0/2191.102.232.1 to 91.102.239.25491.102.239.2552,046
22391.102.240.0/2191.102.240.1 to 91.102.247.25491.102.247.2552,046
22491.102.248.0/2191.102.248.1 to 91.102.255.25491.102.255.2552,046
22591.103.0.0/2191.103.0.1 to 91.103.7.25491.103.7.2552,046
22691.103.8.0/2191.103.8.1 to 91.103.15.25491.103.15.2552,046
22791.103.16.0/2191.103.16.1 to 91.103.23.25491.103.23.2552,046
22891.103.24.0/2191.103.24.1 to 91.103.31.25491.103.31.2552,046
22991.103.32.0/2191.103.32.1 to 91.103.39.25491.103.39.2552,046
23091.103.40.0/2191.103.40.1 to 91.103.47.25491.103.47.2552,046
23191.103.48.0/2191.103.48.1 to 91.103.55.25491.103.55.2552,046
23291.103.56.0/2191.103.56.1 to 91.103.63.25491.103.63.2552,046
23391.103.64.0/2191.103.64.1 to 91.103.71.25491.103.71.2552,046
23491.103.72.0/2191.103.72.1 to 91.103.79.25491.103.79.2552,046
23591.103.80.0/2191.103.80.1 to 91.103.87.25491.103.87.2552,046
23691.103.88.0/2191.103.88.1 to 91.103.95.25491.103.95.2552,046
23791.103.96.0/2191.103.96.1 to 91.103.103.25491.103.103.2552,046
23891.103.104.0/2191.103.104.1 to 91.103.111.25491.103.111.2552,046
23991.103.112.0/2191.103.112.1 to 91.103.119.25491.103.119.2552,046
24091.103.120.0/2191.103.120.1 to 91.103.127.25491.103.127.2552,046
24191.103.128.0/2191.103.128.1 to 91.103.135.25491.103.135.2552,046
24291.103.136.0/2191.103.136.1 to 91.103.143.25491.103.143.2552,046
24391.103.144.0/2191.103.144.1 to 91.103.151.25491.103.151.2552,046
24491.103.152.0/2191.103.152.1 to 91.103.159.25491.103.159.2552,046
24591.103.160.0/2191.103.160.1 to 91.103.167.25491.103.167.2552,046
24691.103.168.0/2191.103.168.1 to 91.103.175.25491.103.175.2552,046
24791.103.176.0/2191.103.176.1 to 91.103.183.25491.103.183.2552,046
24891.103.184.0/2191.103.184.1 to 91.103.191.25491.103.191.2552,046
24991.103.192.0/2191.103.192.1 to 91.103.199.25491.103.199.2552,046
25091.103.200.0/2191.103.200.1 to 91.103.207.25491.103.207.2552,046
25191.103.208.0/2191.103.208.1 to 91.103.215.25491.103.215.2552,046
25291.103.216.0/2191.103.216.1 to 91.103.223.25491.103.223.2552,046
25391.103.224.0/2191.103.224.1 to 91.103.231.25491.103.231.2552,046
25491.103.232.0/2191.103.232.1 to 91.103.239.25491.103.239.2552,046
25591.103.240.0/2191.103.240.1 to 91.103.247.25491.103.247.2552,046
25691.103.248.0/2191.103.248.1 to 91.103.255.25491.103.255.2552,046

IPv4 CIDR reference (/0 to /32)

IPv4 prefix lengths
PrefixSubnet maskWildcardAddressesUsable hostsSizeTypical use
/00.0.0.0255.255.255.2554,294,967,2964,294,967,29416,777,216 × /24
/1128.0.0.0127.255.255.2552,147,483,6482,147,483,6468,388,608 × /24
/2192.0.0.063.255.255.2551,073,741,8241,073,741,8224,194,304 × /24
/3224.0.0.031.255.255.255536,870,912536,870,9102,097,152 × /24
/4240.0.0.015.255.255.255268,435,456268,435,4541,048,576 × /24
/5248.0.0.07.255.255.255134,217,728134,217,726524,288 × /24
/6252.0.0.03.255.255.25567,108,86467,108,862262,144 × /24
/7254.0.0.01.255.255.25533,554,43233,554,430131,072 × /24
/8255.0.0.00.255.255.25516,777,21616,777,21465,536 × /24Old class A; 10.0.0.0/8
/9255.128.0.00.127.255.2558,388,6088,388,60632,768 × /24
/10255.192.0.00.63.255.2554,194,3044,194,30216,384 × /24
/11255.224.0.00.31.255.2552,097,1522,097,1508,192 × /24
/12255.240.0.00.15.255.2551,048,5761,048,5744,096 × /24172.16.0.0/12
/13255.248.0.00.7.255.255524,288524,2862,048 × /24
/14255.252.0.00.3.255.255262,144262,1421,024 × /24
/15255.254.0.00.1.255.255131,072131,070512 × /24
/16255.255.0.00.0.255.25565,53665,534256 × /24Old class B; 192.168.0.0/16
/17255.255.128.00.0.127.25532,76832,766128 × /24
/18255.255.192.00.0.63.25516,38416,38264 × /24
/19255.255.224.00.0.31.2558,1928,19032 × /24
/20255.255.240.00.0.15.2554,0964,09416 × /24
/21255.255.248.00.0.7.2552,0482,0468 × /24
/22255.255.252.00.0.3.2551,0241,0224 × /24Large office or guest Wi-Fi (1,022 hosts)
/23255.255.254.00.0.1.2555125102 × /24Larger office LAN (510 hosts)
/24255.255.255.00.0.0.2552562541 × /24Typical office LAN (old class C)
/25255.255.255.1280.0.0.1271281261/2 of a /24Smaller LAN or VLAN
/26255.255.255.1920.0.0.6364621/4 of a /24Smaller LAN or VLAN
/27255.255.255.2240.0.0.3132301/8 of a /24Small VLAN, phones, cameras
/28255.255.255.2400.0.0.1516141/16 of a /24Small VLAN, phones, cameras
/29255.255.255.2480.0.0.7861/32 of a /24Small fixed public block (5 usable)
/30255.255.255.2520.0.0.3421/64 of a /24Point-to-point (old style)
/31255.255.255.2540.0.0.1221/128 of a /24Point-to-point link (RFC 3021)
/32255.255.255.2550.0.0.0111/256 of a /24One host

IPv6 prefix reference

IPv6 prefix lengths
PrefixAddresses/64 LANs/48 sitesNibbleTypical use
/342,535,295,865,117,307,932,921,825,928,971,026,432 (2^125)2,305,843,009,213,693,95235,184,372,088,832NoAll global unicast (2000::/3)
/165,192,296,858,534,827,628,530,496,329,220,096 (2^112)281,474,976,710,6564,294,967,296Yes
/20324,518,553,658,426,726,783,156,020,576,256 (2^108)17,592,186,044,416268,435,456YesLarge provider allocation (RIPE minimum for some)
/29633,825,300,114,114,700,748,351,602,688 (2^99)34,359,738,368524,288NoRIPE allocation to a provider (often)
/3279,228,162,514,264,337,593,543,950,336 (2^96)4,294,967,29665,536YesProvider allocation (RIPE default)
/364,951,760,157,141,521,099,596,496,896 (2^92)268,435,4564,096Yes
/40309,485,009,821,345,068,724,781,056 (2^88)16,777,216256Yes
/4419,342,813,113,834,066,795,298,816 (2^84)1,048,57616Yes
/481,208,925,819,614,629,174,706,176 (2^80)65,5361YesOne site or organisation (RIPE PI / assignment)
/5275,557,863,725,914,323,419,136 (2^76)4,096Yes
/564,722,366,482,869,645,213,696 (2^72)256YesSmall site or home (common provider assignment)
/60295,147,905,179,352,825,856 (2^68)16YesSome home broadband (16 LANs)
/6418,446,744,073,709,551,616 (2^64)1YesOne LAN or VLAN (needed for SLAAC)
/7272,057,594,037,927,936 (2^56)1/256 of a /64Yes
/80281,474,976,710,656 (2^48)1/65,536 of a /64Yes
/964,294,967,2961/4,294,967,296 of a /64YesEmbeds an IPv4 address (NAT64)
/11265,5361/281,474,976,710,656 of a /64Yes
/1202561/72,057,594,037,927,936 of a /64Yes
/124161/1,152,921,504,606,846,976 of a /64Yes
/12641/4,611,686,018,427,387,904 of a /64No
/12721/9,223,372,036,854,775,808 of a /64NoPoint-to-point link (RFC 6164)
/12811/18,446,744,073,709,551,616 of a /64YesOne host or loopback

Private and special ranges

IPv4

Special-purpose ranges
RangeNameWhat it is
255.255.255.255/32Limited broadcastEvery host on the local network
0.0.0.0/8This networkNot routed; 0.0.0.0 means "any address" in settings
10.0.0.0/8Private (RFC 1918)Office and home networks; not routed on the internet
100.64.0.0/10Shared address space (CGNAT)Used by providers behind carrier-grade NAT (RFC 6598)
127.0.0.0/8LoopbackThis computer
169.254.0.0/16Link-local (APIPA)Self-assigned when no DHCP server answers
172.16.0.0/12Private (RFC 1918)Office and home networks; not routed on the internet
192.0.0.0/24IETF protocol assignmentsSpecial uses such as DS-Lite
192.0.2.0/24Documentation (TEST-NET-1)For examples; never used on a network
192.88.99.0/246to4 relay (deprecated)Formerly anycast for 6to4
192.168.0.0/16Private (RFC 1918)Office and home networks; not routed on the internet
198.18.0.0/15BenchmarkingNetwork equipment testing (RFC 2544)
198.51.100.0/24Documentation (TEST-NET-2)For examples; never used on a network
203.0.113.0/24Documentation (TEST-NET-3)For examples; never used on a network
224.0.0.0/4MulticastOne-to-many traffic, such as IPTV and routing protocols
240.0.0.0/4ReservedFuture use; not usable on most systems

IPv6

Special-purpose ranges
RangeNameWhat it is
::/128UnspecifiedNo address; :: means "any address" in settings
::1/128LoopbackThis computer
::ffff:0:0/96IPv4-mappedAn IPv4 address written as IPv6
64:ff9b::/96NAT64IPv4 addresses reached through a NAT64 gateway
100::/64Discard onlyTraffic sent here is dropped (RFC 6666)
2001:db8::/32DocumentationFor examples; never used on a network
2001::/32TeredoIPv6 tunnelled over IPv4 UDP
2002::/166to4IPv6 tunnelled over IPv4 (largely retired)
3fff::/20DocumentationFor examples (RFC 9637)
fc00::/7Unique local (ULA)Private IPv6, like RFC 1918; usually fd00::/8
fe80::/10Link-localEvery IPv6 interface has one; not routed
ff00::/8MulticastOne-to-many traffic; replaces broadcast
2000::/3Global unicastPublic internet addresses

About this tool

A network is written as an address and a prefix length, such as 192.168.1.0/24: the first 24 bits name the network and the rest number the devices on it. The calculator works out where the network starts and ends, how many devices it holds, its subnet and wildcard masks, and the reverse DNS zone to ask your provider for.

It also splits a network into equal smaller ones (one per VLAN or site), turns a range of addresses into the fewest CIDR blocks for a firewall rule, and lists every IPv4 prefix length and the common IPv6 ones in reference tables.

Common questions

Why are two addresses lost in every IPv4 subnet?

The first address names the network and the last is the broadcast address, so a /24 has 256 addresses but 254 for devices. A /31 (a link between two routers) and a /32 (one host) are the exceptions.

What size of IPv6 network should a LAN use?

Always /64. Devices pick their own address within it (SLAAC), which needs the full 64 bits. A site usually gets a /48 or /56 from its provider, which holds 65,536 or 256 LANs.

What is a wildcard mask?

The subnet mask turned inside out: 255.255.255.0 becomes 0.0.0.255. Cisco access lists and OSPF use it to say which bits must match.

Which ranges can I use inside an office?

IPv4: 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. IPv6: unique local addresses from fd00::/8, though most networks use the public prefix from their provider.